TXX-6033, Interim Deficiency Rept CP-86-14 Re Brown Boveri 6.9 Kv Switchgear Breaker Jack Shaft Weld Failure.Initially Reported on 860311.Vendor Initiated Evaluation of Design Criteria.Next Rept Will Be Submitted by 861219
| ML20215L058 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/20/1986 |
| From: | Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| CP-86-14, TXX-6033, NUDOCS 8610280446 | |
| Download: ML20215L058 (2) | |
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s Log # TXX-6033 File # 10110 908.3 TEXAS UTILITIES GENERATING COMPANY SKYWAY TOWER 480 NORTH LLIVE STREET. E.B. 88. DALLAS. TEXAR 75201 October 20, 1986 EM"iffE*i T]gg i
ser2 i ses e.,
6 Mr. Eric H. Johnson, Director j
Division of Reactor Safety and Projects U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76012
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NOS. 50-445 AND 50-446 6.9KV SWITCHGEAR BREAKER JACK SHAFT WELD FAILURE SDAR: CP-86-14 (INTERIM REPORT)
Dear Mr. Johnson:
On March 11, 1986, we verbally notified your Mr. T. F. Westerman of a deficiency involving a weld failure in a component of a Class 1E 6.9kv switchgear breaker. This is an interim report of a potentially reportable item under the provisions of 10CFR50.55(e). Our latest interim report, logged TXX-4941, was submitted on July 29, 1986.
During normal maintenance, a 6.9kv switchgear breaker (IA3 cubicle 7: service air compressor) was closed and reopened automatically due to a phase imbalance. Our subsequent investigation revealed that a weld connecting the right hand jack shaft and the lever arm had failed due to inadequate weld fusion. The defective breaker was replaced with a spare.
During a subsequent common mode failure analysis, a visual inspection program of all critical breakers and a statistical random sample check on the non-critical breakers was completed using acceptance criteria provided by the breaker manufacturer (Brown Boveri). The initial results of this inspection concluded that the jack shaft welds did not meet the vendor's acceptance criteria in all cases.
As a result of these findings, the vendor has initiated an evaluation of the established design criteria, including design testing to verify breaker operability. Our assessment of this issue is contingent upon completion and review of Brown Boveri's evaluation.
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O TXX-6033 October 20, 1986 4
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We anticipate submitting our next report by December 19, 1986.
- i Very truly yours, 4Gur W. G. Counsil l
JCH/mlh c - NRC Region IV (0 + 1 copy) i Director, Inspection & Enforcement (15 copies)
U. S. Nuclear Regulatory Commission Washington, D.C.
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